Around 5:40 a.m. Sunday, a 26-year-old woman was walking in the 1000 block of North Dearborn Street when a man approached her from behind, said Chicago Police Department News Affairs Officer Jose Estrada.

The man dragged her into an alley and threw her to the ground, Estrada said. A nearby witness was able to scare off the attacker, Estrada said. The woman was taken to Northwestern Memorial Hospital, he said.

Another woman was attacked in the evening hours of June 17 on the 1100 block of North Clark Street, about two blocks away from the most recent assault, police said. The attacker approached that woman from behind as well and pulled the victim into an alley and sexually assaulted her.

Police described the attacker as a black man between the ages of 35 to 45. He has a dark brown complexion and is about 5 feet, 9 inches to 6 feet, 2 inches tall. He weighs between 240 and 260 pounds, police said.

The attacker was last seen wearing a dark blue tank top, white shirt and blue jean shorts.

Anyone with information about the attacks should contact the Area Central Bureau of Detectives at (312) 747-8380.